Selected Correspondence:
Letter 30 (17) Spinoza to Peter Balling [N1]

Beloved Friend, --Your last letter, written, if I
mistake not, on the 26th of last month, has duly reached me. It caused
me no small sorrow and solicitude, though the feeling
sensibly diminished when I reflected on the good sense and
fortitude, with which you have known how to despise the
evils of fortune, or rather of opinion, at a time when they
most bitterly assailed you. Yet my anxiety increases daily;
I therefore beg and implore you by the claims of our
friendship, that you will rouse yourself to write me a long
letter. With regard to Omens, of which you make mention
in telling me that, while your child was still healthy and strong,
you heard groans like those he uttered when he was
ill and shortly afterwards died, I should judge that these were not
real groans, but only the effect of your
imagination;
for you say that, when you got up and composed yourself to listen,
you did not hear them so clearly either as before
or as afterwards, when you had fallen asleep again. This, I think,
shows that the groans were purely due to the
imagination,
which, when it was unfettered and free, could
imagine groans more forcibly and vividly than when you
sat up in order to listen in a particular direction. I think
I can both illustrate and confirm what I say by another
occurrence, which befell me at Rhijnsburg last winter. When
one morning, after the day had dawned, I woke up from
a very unpleasant dream, the
images, which had presented
themselves to me in sleep, remained before my eyes
just as vividly as though the things had been real, especially
the image
of a certain black and leprous Brazilian
whom I had never seen before. This
image disappeared for the
most part when, in order to divert my thoughts, I
cast my eyes on a book, or something else. But, as soon as I
lifted my eyes again without fixing my attention on
any particular object, the same
image of this same negro
appeared with the same vividness again and again, until
the head of it gradually vanished. I say that the same thing,
which occurred with regard to my inward sense of sight,
occurred with your hearing; but as the causes were very different,
your case was an omen and mine was not. The
matter may be clearly grasped by means of what I am about to say.
The effects of the imagination
arise either from
bodily or mental causes. I will proceed to prove this, in order not
to be too long, solely from experience. We know
that fevers and other bodily ailments are the causes of delirium,
and that persons of stubborn disposition imagine
nothing but quarrels, brawls, slaughterings, and the like. We also
see that the imagination
is to a certain extent
determined by the character of the disposition, for, as we know by
experience, it follows in the tracks of the
understanding
in every respect, and arranges its
images and
words,
just as the understanding
arranges its
demonstrations and connects one with another; so that we are
hardly at all able to say, what will not serve the
imagination
as a basis for some image
or other. This being so,
I say that no effects of imagination
springing from
physical causes can ever be omens of future events; inasmuch
as their causes do not involve any future events. But
the effects of imagination,
or images originating in the mental
disposition, may be omens of some future event;
inasmuch as the mind may have a confused presentiment of the
future. It may, therefore, imagine a future event as
forcibly and vividly, as though it were present; for instance
a father (to take an example resembling your own) loves
his child so much, that he and the beloved child are, as it
were, one and the same. And since (like that which I
demonstrated on another occasion) there must necessarily exist
in thought the idea of the
essence of the child's
states and their results, and since the father, through his union
with his child, is a part of the said child, the soul of
the father must necessarily participate in the ideal
essence of the
child and his states, and in their results, as I have
shown at greater length elsewhere.

Again, as the soul of the father participates ideally in the
consequences of his child's
essence, he may (as I have
said) sometimes imagine some of the said consequences as vividly
as if they were present with him, provided that
the following conditions are fulfilled: --I. If the occurrence in
his son's career be remarkable. II. If it be capable of being
readily imagined.
III. If the time of its happening be not too
remote. IV. If his body be sound, in respect not only of
health but of freedom from every care or business which could
outwardly trouble the senses. It may also assist the
result, if we think of something which generally stimulates
similar ideas. For instance, if while we are talking with
this or that man we hear groans, it will generally happen
that, when we think of the man again, the groans heard
when we spoke with him will recur to our mind. This, dear
friend, is my Opinion on the question you ask me. I have, I
confess, been very brief, but I have furnished you with material
for writing to me on the first opportunity, &c.

Voorburg, 20 July, 1664.

[Note N1]: This letter is from a Latin version of a Dutch original.
For Balling, see Letter 26, and note there.